Construction of, and T-helper (Th)1/Th2 immune responses to, a herpes simplex virus type 2 glycoprotein D-cytotoxic T-lymphocyte epitope DNA vaccine

Abstract

Recombinant cytotoxic T lymphocyte (CTL) epitope DNA vaccines offer an attractive approach for the induction of robust cellular and humoral immune responses directed against human pathogen target antigens. To construct a pVAX-gD-CTL vector expressing the glycoprotein (g)D and gB CTL epitopes from herpes simplex virus type 2 (HSV2) and evaluate it in mice for immunogenicity and protective efficacy against intraperitoneal challenge with the HSV2 strain Sav. The gD gene transcript and gB CTL epitope were inserted into the pVAX vector to obtain the recombinant plasmid pVAX-gD-CTL. An in vitro study was then conducted to detect the expression of gD by immunocytochemistry and western blotting. BALB/c mice were immunized with this DNA vaccine, then the CTL activity and expression of anti-HSV2 gD IgG, interferon-gamma and interleukin-4 by lactate dehydrogenase release assay and ELISA, respectively. The protection given to the mice was assayed by a fatal dose of virus. The pVAX-gD-CTL vector was successfully constructed and could express gD in COS-7 cells. Immunogenicity of gD, anti-HSV2 gD neutralizing serum IgG antibody and robust Th1-polarized immune responses were found. Furthermore, mice were prophylactically protected from challenge with a high dose of HSV2. In summary, pVAX-gD-CTL vector was successfully used to elicit potent Th1-like cellular and humoral immune responses that were protective against HSV2 disease in mice.